Interconnect structure having a carbon-containing barrier layer

Abstract

An interconnect structure and a method of forming an interconnect structure are disclosed. The interconnect structure includes a conductive plug over a substrate; a conductive feature over the conductive plug, wherein the conductive feature has a first sidewall, a second sidewall facing the first sidewall, and a bottom surface; and a carbon-containing barrier layer having a first portion along the first sidewall of the conductive feature, a second portion along the second sidewall of the conductive feature, and a third portion along the bottom surface of the conductive feature.

What is claimed is: 
     
       1. An interconnect structure, comprising:
 a first dielectric layer over a substrate; 
 a first conductive feature in the first dielectric layer, wherein the first conductive feature comprises a void; 
 a second dielectric layer over the first dielectric layer; 
 a third dielectric layer over the second dielectric layer, the second dielectric layer and the third dielectric layer having a trench extending from an upper surface of the third dielectric layer to the first dielectric layer, wherein the trench extends into the first dielectric layer, wherein the trench exposes the void in the first conductive feature; 
 a carbon-containing barrier layer along surfaces of the trench, wherein the carbon-containing barrier layer lines the void; and 
 a second conductive feature over the carbon-containing barrier layer in the trench. 
 
     
     
       2. The interconnect structure of  claim 1 , wherein an upper surface of the first conductive feature is lower than an upper surface of the first dielectric layer. 
     
     
       3. The interconnect structure of  claim 1 , wherein the first conductive feature comprises tungsten. 
     
     
       4. The interconnect structure of  claim 1 , wherein the second conductive feature comprises copper. 
     
     
       5. The interconnect structure of  claim 1 , wherein the carbon-containing barrier layer comprises tantalum nitride (TaN), and an atomic ratio of N divided by Ta is from about 2.3 to about 2.6. 
     
     
       6. The interconnect structure of  claim 1 , wherein a ratio of a sidewall thickness of the carbon-containing barrier layer to a bottom thickness of the carbon-containing barrier layer is between 0.9 and 1.1. 
     
     
       7. The interconnect structure of  claim 1 , wherein a thickness of the carbon-containing barrier layer is from 4.5 Angstroms to 55 Angstroms. 
     
     
       8. An interconnect structure comprising:
 a lower dielectric layer over a substrate, the lower dielectric layer having a first recess; 
 a first conductive feature in the first recess, the first conductive feature having a void; 
 an upper dielectric layer over the lower dielectric layer, the upper dielectric layer having a second recess, wherein the second recess extends to the first conductive feature, the second recess extending into the lower dielectric layer; 
 a carbon-containing layer along sidewalls of the void; and 
 a second conductive feature over the carbon-containing layer. 
 
     
     
       9. The interconnect structure of  claim 8 , the carbon-containing layer has a carbon concentration of at least about 0.1 atomic percent (at %). 
     
     
       10. The interconnect structure of  claim 8 , wherein an upper surface of the carbon-containing layer along a bottom of the second recess is lower than an upper surface of the lower dielectric layer. 
     
     
       11. The interconnect structure of  claim 8 , further comprising a cap layer over the second conductive feature. 
     
     
       12. The interconnect structure of  claim 11 , wherein the cap layer has a composition of MxOyNz, where M is a metal, O is oxygen, and N is nitrogen. 
     
     
       13. The interconnect structure of  claim 12 , wherein the metal is selected from the group consisting essentially of Al, Mn, Co, Ti, Ta, W, Ni, Sn, Mg, and combinations thereof. 
     
     
       14. An interconnect structure, comprising:
 a first dielectric layer; 
 a first recess in the first dielectric layer; 
 a first conductive feature in the first recess, the first conductive feature having a void; 
 a second dielectric layer over the first dielectric layer; 
 a second recess through the second dielectric layer and into the first dielectric layer; 
 a carbon-containing tantalum nitride layer along sidewalls of the second recess and sidewalls of the void; and 
 a second conductive layer over the carbon-containing tantalum nitride layer. 
 
     
     
       15. The interconnect structure of  claim 14 , wherein the carbon-containing tantalum nitride layer extends continuously from an upper surface of the second dielectric layer to a bottom of the void. 
     
     
       16. The interconnect structure of  claim 14 , wherein the carbon-containing tantalum nitride layer has a carbon concentration from 0.2 at % to 1 at %. 
     
     
       17. The interconnect structure of  claim 14 , wherein a thickness of the carbon-containing tantalum nitride layer along a sidewall of the second dielectric layer is in a range from about 4.5 angstroms (Å) to about 55 angstroms (Å). 
     
     
       18. The interconnect structure of  claim 14 , wherein a thickness of the carbon-containing tantalum nitride layer along an upper surface of the first dielectric layer is in a range from about 5 angstroms (Å) to about 50 angstroms (Å). 
     
     
       19. The interconnect structure of  claim 14 , the carbon-containing tantalum nitride layer completely seals the void. 
     
     
       20. The interconnect structure of  claim 14 , wherein the second conductive layer extends below an upper surface of the first dielectric layer.